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<pre><span class="sourceLineNo">001</span>/*<a name="line.1"></a>
<span class="sourceLineNo">002</span> * Copyright (C) 2008 The Guava Authors<a name="line.2"></a>
<span class="sourceLineNo">003</span> *<a name="line.3"></a>
<span class="sourceLineNo">004</span> * Licensed under the Apache License, Version 2.0 (the "License");<a name="line.4"></a>
<span class="sourceLineNo">005</span> * you may not use this file except in compliance with the License.<a name="line.5"></a>
<span class="sourceLineNo">006</span> * You may obtain a copy of the License at<a name="line.6"></a>
<span class="sourceLineNo">007</span> *<a name="line.7"></a>
<span class="sourceLineNo">008</span> * http://www.apache.org/licenses/LICENSE-2.0<a name="line.8"></a>
<span class="sourceLineNo">009</span> *<a name="line.9"></a>
<span class="sourceLineNo">010</span> * Unless required by applicable law or agreed to in writing, software<a name="line.10"></a>
<span class="sourceLineNo">011</span> * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.11"></a>
<span class="sourceLineNo">012</span> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.12"></a>
<span class="sourceLineNo">013</span> * See the License for the specific language governing permissions and<a name="line.13"></a>
<span class="sourceLineNo">014</span> * limitations under the License.<a name="line.14"></a>
<span class="sourceLineNo">015</span> */<a name="line.15"></a>
<span class="sourceLineNo">016</span><a name="line.16"></a>
<span class="sourceLineNo">017</span>package com.google.common.io;<a name="line.17"></a>
<span class="sourceLineNo">018</span><a name="line.18"></a>
<span class="sourceLineNo">019</span>import com.google.common.annotations.Beta;<a name="line.19"></a>
<span class="sourceLineNo">020</span>import com.google.common.annotations.VisibleForTesting;<a name="line.20"></a>
<span class="sourceLineNo">021</span><a name="line.21"></a>
<span class="sourceLineNo">022</span>import java.io.ByteArrayInputStream;<a name="line.22"></a>
<span class="sourceLineNo">023</span>import java.io.ByteArrayOutputStream;<a name="line.23"></a>
<span class="sourceLineNo">024</span>import java.io.File;<a name="line.24"></a>
<span class="sourceLineNo">025</span>import java.io.FileInputStream;<a name="line.25"></a>
<span class="sourceLineNo">026</span>import java.io.FileOutputStream;<a name="line.26"></a>
<span class="sourceLineNo">027</span>import java.io.IOException;<a name="line.27"></a>
<span class="sourceLineNo">028</span>import java.io.InputStream;<a name="line.28"></a>
<span class="sourceLineNo">029</span>import java.io.OutputStream;<a name="line.29"></a>
<span class="sourceLineNo">030</span><a name="line.30"></a>
<span class="sourceLineNo">031</span>/**<a name="line.31"></a>
<span class="sourceLineNo">032</span> * An {@link OutputStream} that starts buffering to a byte array, but<a name="line.32"></a>
<span class="sourceLineNo">033</span> * switches to file buffering once the data reaches a configurable size.<a name="line.33"></a>
<span class="sourceLineNo">034</span> *<a name="line.34"></a>
<span class="sourceLineNo">035</span> * &lt;p&gt;This class is thread-safe.<a name="line.35"></a>
<span class="sourceLineNo">036</span> *<a name="line.36"></a>
<span class="sourceLineNo">037</span> * @author Chris Nokleberg<a name="line.37"></a>
<span class="sourceLineNo">038</span> * @since 1.0<a name="line.38"></a>
<span class="sourceLineNo">039</span> */<a name="line.39"></a>
<span class="sourceLineNo">040</span>@Beta<a name="line.40"></a>
<span class="sourceLineNo">041</span>public final class FileBackedOutputStream extends OutputStream {<a name="line.41"></a>
<span class="sourceLineNo">042</span><a name="line.42"></a>
<span class="sourceLineNo">043</span>  private final int fileThreshold;<a name="line.43"></a>
<span class="sourceLineNo">044</span>  private final boolean resetOnFinalize;<a name="line.44"></a>
<span class="sourceLineNo">045</span>  private final InputSupplier&lt;InputStream&gt; supplier;<a name="line.45"></a>
<span class="sourceLineNo">046</span><a name="line.46"></a>
<span class="sourceLineNo">047</span>  private OutputStream out;<a name="line.47"></a>
<span class="sourceLineNo">048</span>  private MemoryOutput memory;<a name="line.48"></a>
<span class="sourceLineNo">049</span>  private File file;<a name="line.49"></a>
<span class="sourceLineNo">050</span><a name="line.50"></a>
<span class="sourceLineNo">051</span>  /** ByteArrayOutputStream that exposes its internals. */<a name="line.51"></a>
<span class="sourceLineNo">052</span>  private static class MemoryOutput extends ByteArrayOutputStream {<a name="line.52"></a>
<span class="sourceLineNo">053</span>    byte[] getBuffer() {<a name="line.53"></a>
<span class="sourceLineNo">054</span>      return buf;<a name="line.54"></a>
<span class="sourceLineNo">055</span>    }<a name="line.55"></a>
<span class="sourceLineNo">056</span><a name="line.56"></a>
<span class="sourceLineNo">057</span>    int getCount() {<a name="line.57"></a>
<span class="sourceLineNo">058</span>      return count;<a name="line.58"></a>
<span class="sourceLineNo">059</span>    }<a name="line.59"></a>
<span class="sourceLineNo">060</span>  }<a name="line.60"></a>
<span class="sourceLineNo">061</span><a name="line.61"></a>
<span class="sourceLineNo">062</span>  /** Returns the file holding the data (possibly null). */<a name="line.62"></a>
<span class="sourceLineNo">063</span>  @VisibleForTesting synchronized File getFile() {<a name="line.63"></a>
<span class="sourceLineNo">064</span>    return file;<a name="line.64"></a>
<span class="sourceLineNo">065</span>  }<a name="line.65"></a>
<span class="sourceLineNo">066</span><a name="line.66"></a>
<span class="sourceLineNo">067</span>  /**<a name="line.67"></a>
<span class="sourceLineNo">068</span>   * Creates a new instance that uses the given file threshold, and does<a name="line.68"></a>
<span class="sourceLineNo">069</span>   * not reset the data when the {@link InputSupplier} returned by<a name="line.69"></a>
<span class="sourceLineNo">070</span>   * {@link #getSupplier} is finalized.<a name="line.70"></a>
<span class="sourceLineNo">071</span>   *<a name="line.71"></a>
<span class="sourceLineNo">072</span>   * @param fileThreshold the number of bytes before the stream should<a name="line.72"></a>
<span class="sourceLineNo">073</span>   *     switch to buffering to a file<a name="line.73"></a>
<span class="sourceLineNo">074</span>   */<a name="line.74"></a>
<span class="sourceLineNo">075</span>  public FileBackedOutputStream(int fileThreshold) {<a name="line.75"></a>
<span class="sourceLineNo">076</span>    this(fileThreshold, false);<a name="line.76"></a>
<span class="sourceLineNo">077</span>  }<a name="line.77"></a>
<span class="sourceLineNo">078</span><a name="line.78"></a>
<span class="sourceLineNo">079</span>  /**<a name="line.79"></a>
<span class="sourceLineNo">080</span>   * Creates a new instance that uses the given file threshold, and<a name="line.80"></a>
<span class="sourceLineNo">081</span>   * optionally resets the data when the {@link InputSupplier} returned<a name="line.81"></a>
<span class="sourceLineNo">082</span>   * by {@link #getSupplier} is finalized.<a name="line.82"></a>
<span class="sourceLineNo">083</span>   *<a name="line.83"></a>
<span class="sourceLineNo">084</span>   * @param fileThreshold the number of bytes before the stream should<a name="line.84"></a>
<span class="sourceLineNo">085</span>   *     switch to buffering to a file<a name="line.85"></a>
<span class="sourceLineNo">086</span>   * @param resetOnFinalize if true, the {@link #reset} method will<a name="line.86"></a>
<span class="sourceLineNo">087</span>   *     be called when the {@link InputSupplier} returned by {@link<a name="line.87"></a>
<span class="sourceLineNo">088</span>   *     #getSupplier} is finalized<a name="line.88"></a>
<span class="sourceLineNo">089</span>   */<a name="line.89"></a>
<span class="sourceLineNo">090</span>  public FileBackedOutputStream(int fileThreshold, boolean resetOnFinalize) {<a name="line.90"></a>
<span class="sourceLineNo">091</span>    this.fileThreshold = fileThreshold;<a name="line.91"></a>
<span class="sourceLineNo">092</span>    this.resetOnFinalize = resetOnFinalize;<a name="line.92"></a>
<span class="sourceLineNo">093</span>    memory = new MemoryOutput();<a name="line.93"></a>
<span class="sourceLineNo">094</span>    out = memory;<a name="line.94"></a>
<span class="sourceLineNo">095</span><a name="line.95"></a>
<span class="sourceLineNo">096</span>    if (resetOnFinalize) {<a name="line.96"></a>
<span class="sourceLineNo">097</span>      supplier = new InputSupplier&lt;InputStream&gt;() {<a name="line.97"></a>
<span class="sourceLineNo">098</span>        @Override<a name="line.98"></a>
<span class="sourceLineNo">099</span>        public InputStream getInput() throws IOException {<a name="line.99"></a>
<span class="sourceLineNo">100</span>          return openStream();<a name="line.100"></a>
<span class="sourceLineNo">101</span>        }<a name="line.101"></a>
<span class="sourceLineNo">102</span><a name="line.102"></a>
<span class="sourceLineNo">103</span>        @Override protected void finalize() {<a name="line.103"></a>
<span class="sourceLineNo">104</span>          try {<a name="line.104"></a>
<span class="sourceLineNo">105</span>            reset();<a name="line.105"></a>
<span class="sourceLineNo">106</span>          } catch (Throwable t) {<a name="line.106"></a>
<span class="sourceLineNo">107</span>            t.printStackTrace(System.err);<a name="line.107"></a>
<span class="sourceLineNo">108</span>          }<a name="line.108"></a>
<span class="sourceLineNo">109</span>        }<a name="line.109"></a>
<span class="sourceLineNo">110</span>      };<a name="line.110"></a>
<span class="sourceLineNo">111</span>    } else {<a name="line.111"></a>
<span class="sourceLineNo">112</span>      supplier = new InputSupplier&lt;InputStream&gt;() {<a name="line.112"></a>
<span class="sourceLineNo">113</span>        @Override<a name="line.113"></a>
<span class="sourceLineNo">114</span>        public InputStream getInput() throws IOException {<a name="line.114"></a>
<span class="sourceLineNo">115</span>          return openStream();<a name="line.115"></a>
<span class="sourceLineNo">116</span>        }<a name="line.116"></a>
<span class="sourceLineNo">117</span>      };<a name="line.117"></a>
<span class="sourceLineNo">118</span>    }<a name="line.118"></a>
<span class="sourceLineNo">119</span>  }<a name="line.119"></a>
<span class="sourceLineNo">120</span><a name="line.120"></a>
<span class="sourceLineNo">121</span>  /**<a name="line.121"></a>
<span class="sourceLineNo">122</span>   * Returns a supplier that may be used to retrieve the data buffered<a name="line.122"></a>
<span class="sourceLineNo">123</span>   * by this stream.<a name="line.123"></a>
<span class="sourceLineNo">124</span>   */<a name="line.124"></a>
<span class="sourceLineNo">125</span>  public InputSupplier&lt;InputStream&gt; getSupplier() {<a name="line.125"></a>
<span class="sourceLineNo">126</span>    return supplier;<a name="line.126"></a>
<span class="sourceLineNo">127</span>  }<a name="line.127"></a>
<span class="sourceLineNo">128</span><a name="line.128"></a>
<span class="sourceLineNo">129</span>  private synchronized InputStream openStream() throws IOException {<a name="line.129"></a>
<span class="sourceLineNo">130</span>    if (file != null) {<a name="line.130"></a>
<span class="sourceLineNo">131</span>      return new FileInputStream(file);<a name="line.131"></a>
<span class="sourceLineNo">132</span>    } else {<a name="line.132"></a>
<span class="sourceLineNo">133</span>      return new ByteArrayInputStream(<a name="line.133"></a>
<span class="sourceLineNo">134</span>          memory.getBuffer(), 0, memory.getCount());<a name="line.134"></a>
<span class="sourceLineNo">135</span>    }<a name="line.135"></a>
<span class="sourceLineNo">136</span>  }<a name="line.136"></a>
<span class="sourceLineNo">137</span><a name="line.137"></a>
<span class="sourceLineNo">138</span>  /**<a name="line.138"></a>
<span class="sourceLineNo">139</span>   * Calls {@link #close} if not already closed, and then resets this<a name="line.139"></a>
<span class="sourceLineNo">140</span>   * object back to its initial state, for reuse. If data was buffered<a name="line.140"></a>
<span class="sourceLineNo">141</span>   * to a file, it will be deleted.<a name="line.141"></a>
<span class="sourceLineNo">142</span>   *<a name="line.142"></a>
<span class="sourceLineNo">143</span>   * @throws IOException if an I/O error occurred while deleting the file buffer<a name="line.143"></a>
<span class="sourceLineNo">144</span>   */<a name="line.144"></a>
<span class="sourceLineNo">145</span>  public synchronized void reset() throws IOException {<a name="line.145"></a>
<span class="sourceLineNo">146</span>    try {<a name="line.146"></a>
<span class="sourceLineNo">147</span>      close();<a name="line.147"></a>
<span class="sourceLineNo">148</span>    } finally {<a name="line.148"></a>
<span class="sourceLineNo">149</span>      if (memory == null) {<a name="line.149"></a>
<span class="sourceLineNo">150</span>        memory = new MemoryOutput();<a name="line.150"></a>
<span class="sourceLineNo">151</span>      } else {<a name="line.151"></a>
<span class="sourceLineNo">152</span>        memory.reset();<a name="line.152"></a>
<span class="sourceLineNo">153</span>      }<a name="line.153"></a>
<span class="sourceLineNo">154</span>      out = memory;<a name="line.154"></a>
<span class="sourceLineNo">155</span>      if (file != null) {<a name="line.155"></a>
<span class="sourceLineNo">156</span>        File deleteMe = file;<a name="line.156"></a>
<span class="sourceLineNo">157</span>        file = null;<a name="line.157"></a>
<span class="sourceLineNo">158</span>        if (!deleteMe.delete()) {<a name="line.158"></a>
<span class="sourceLineNo">159</span>          throw new IOException("Could not delete: " + deleteMe);<a name="line.159"></a>
<span class="sourceLineNo">160</span>        }<a name="line.160"></a>
<span class="sourceLineNo">161</span>      }<a name="line.161"></a>
<span class="sourceLineNo">162</span>    }<a name="line.162"></a>
<span class="sourceLineNo">163</span>  }<a name="line.163"></a>
<span class="sourceLineNo">164</span><a name="line.164"></a>
<span class="sourceLineNo">165</span>  @Override public synchronized void write(int b) throws IOException {<a name="line.165"></a>
<span class="sourceLineNo">166</span>    update(1);<a name="line.166"></a>
<span class="sourceLineNo">167</span>    out.write(b);<a name="line.167"></a>
<span class="sourceLineNo">168</span>  }<a name="line.168"></a>
<span class="sourceLineNo">169</span><a name="line.169"></a>
<span class="sourceLineNo">170</span>  @Override public synchronized void write(byte[] b) throws IOException {<a name="line.170"></a>
<span class="sourceLineNo">171</span>    write(b, 0, b.length);<a name="line.171"></a>
<span class="sourceLineNo">172</span>  }<a name="line.172"></a>
<span class="sourceLineNo">173</span><a name="line.173"></a>
<span class="sourceLineNo">174</span>  @Override public synchronized void write(byte[] b, int off, int len)<a name="line.174"></a>
<span class="sourceLineNo">175</span>      throws IOException {<a name="line.175"></a>
<span class="sourceLineNo">176</span>    update(len);<a name="line.176"></a>
<span class="sourceLineNo">177</span>    out.write(b, off, len);<a name="line.177"></a>
<span class="sourceLineNo">178</span>  }<a name="line.178"></a>
<span class="sourceLineNo">179</span><a name="line.179"></a>
<span class="sourceLineNo">180</span>  @Override public synchronized void close() throws IOException {<a name="line.180"></a>
<span class="sourceLineNo">181</span>    out.close();<a name="line.181"></a>
<span class="sourceLineNo">182</span>  }<a name="line.182"></a>
<span class="sourceLineNo">183</span><a name="line.183"></a>
<span class="sourceLineNo">184</span>  @Override public synchronized void flush() throws IOException {<a name="line.184"></a>
<span class="sourceLineNo">185</span>    out.flush();<a name="line.185"></a>
<span class="sourceLineNo">186</span>  }<a name="line.186"></a>
<span class="sourceLineNo">187</span><a name="line.187"></a>
<span class="sourceLineNo">188</span>  /**<a name="line.188"></a>
<span class="sourceLineNo">189</span>   * Checks if writing {@code len} bytes would go over threshold, and<a name="line.189"></a>
<span class="sourceLineNo">190</span>   * switches to file buffering if so.<a name="line.190"></a>
<span class="sourceLineNo">191</span>   */<a name="line.191"></a>
<span class="sourceLineNo">192</span>  private void update(int len) throws IOException {<a name="line.192"></a>
<span class="sourceLineNo">193</span>    if (file == null &amp;&amp; (memory.getCount() + len &gt; fileThreshold)) {<a name="line.193"></a>
<span class="sourceLineNo">194</span>      File temp = File.createTempFile("FileBackedOutputStream", null);<a name="line.194"></a>
<span class="sourceLineNo">195</span>      if (resetOnFinalize) {<a name="line.195"></a>
<span class="sourceLineNo">196</span>        // Finalizers are not guaranteed to be called on system shutdown;<a name="line.196"></a>
<span class="sourceLineNo">197</span>        // this is insurance.<a name="line.197"></a>
<span class="sourceLineNo">198</span>        temp.deleteOnExit();<a name="line.198"></a>
<span class="sourceLineNo">199</span>      }<a name="line.199"></a>
<span class="sourceLineNo">200</span>      FileOutputStream transfer = new FileOutputStream(temp);<a name="line.200"></a>
<span class="sourceLineNo">201</span>      transfer.write(memory.getBuffer(), 0, memory.getCount());<a name="line.201"></a>
<span class="sourceLineNo">202</span>      transfer.flush();<a name="line.202"></a>
<span class="sourceLineNo">203</span><a name="line.203"></a>
<span class="sourceLineNo">204</span>      // We've successfully transferred the data; switch to writing to file<a name="line.204"></a>
<span class="sourceLineNo">205</span>      out = transfer;<a name="line.205"></a>
<span class="sourceLineNo">206</span>      file = temp;<a name="line.206"></a>
<span class="sourceLineNo">207</span>      memory = null;<a name="line.207"></a>
<span class="sourceLineNo">208</span>    }<a name="line.208"></a>
<span class="sourceLineNo">209</span>  }<a name="line.209"></a>
<span class="sourceLineNo">210</span>}<a name="line.210"></a>




























































</pre>
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